Battery and Brake lights are on.

[ifyouaint1sturlast]

Hey guys,
My battery and brake lights are on. Car has been sitting for a few weeks. Had the alt and battery checked, alt was good and battery was bad. Bought a new battery. Now the car starts without being jumped (new batteries are awesome) .. but the light is still on. It's obviously a wiring issue.. would the primary suspect be the plug behind the alternator?

Specs:
91 with Aristo swap on stock Aristo electronics
Battery is relocated to trunk

-Never had an issue before the car sat
-The car starts and runs fine with no sign of an electrical issue

Thanks

 

[IBoughtASupra]

What's the alternator charging at? Also, yes, the plug behind the alternator has a lot to do with the battery light. Take a look and see if any wires are broken.

 

[ifyouaint1sturlast]

I did the wiggle test to no avail. I'll test for continuity soon. Obviously the alt is putting out the right signals because when they did the test it verifies those signals as well.

Time to whip out the meter. I'll be back.

 

[CyFi6]

Yeah make sure you have proper charging voltage with the engine running. Anything that causes the battery light to illuminate will also cause the tail lamp failure light as well as the brake light to illuminate, so it is a charging issue. Make sure the belt is tight and in good shape, make sure al connections are clean and tight, check the fusible link, and go from there.

 

[Wildfire007]

Had same problem and it was alternator dieing. Wouldn't start having issues till 20-30 min of driving.

 

[ifyouaint1sturlast]

As I said. The alt was checked. I'll start checking the wiring.

 

[Wildfire007]

Mine was too then it died completely a week later.
A new one is like 80 and solved my problems.

 

[ifyouaint1sturlast]

Mine was too then it died completely a week later.
A new one is like 80 and solved my problems.

Okay. First thing I will do is borrow one to test. Thanks.

 

[JSeaman]

Definitely sounds like alternator - what was it charging at? I've had them both over and under charge prior to failure on Supras

 

[ifyouaint1sturlast]

Well..

Took a meter to the alt. Between the charging post and ground I was getting 1v at high idle. 12v at the battery meaning not charging. Could this still be a problem with the plug on the back of the alt, or would the post output voltage no matter what if the alt was running?

If I'm correct. The plug is like this:
SENSE - Connected to battery voltage to sense if it's charging (12v+ I assume)
IG - Connected to the ignition switch to indicate the key is turned
LAMP - Connected to the light on the dash, illuminated if IG is on and SENSE isn't pulling the right voltage

The only scenario I can come up with is that if the IG wire isn't connected properly, the regulator won't turn on, and the battery won't charge.

Thanks..

 

[ifyouaint1sturlast]

The reason I question that it's not DEAD is because I took it to AutoZone and it passed all the tests. So I highly suspect my vehicles electrical as the AutoZone machine is a contained environment outputting the right signals. Then I hook it up to my car.. and it's not? Makes too much sense to just assume it's dead.

 

[raysupra]

the post on the alternator should have the hishest output of power on the whole vehicle either being a 12vconstantly or a little more when charging. iirc

 

[ifyouaint1sturlast]

the post on the alternator should have the hishest output of power on the whole vehicle either being a 12vconstantly or a little more when charging. iirc

My real question was if the IG signal was not hooked up properly would the post still output any voltage. Thanks.

 

[CyFi6]

Even if the alternator was completely hollowed out, you should have at least battery voltage to the positive post of the alternator. Did you check the fusible link?

 

[ifyouaint1sturlast]

Even if the alternator was completely hollowed out, you should have at least battery voltage to the positive post of the alternator. Did you check the fusible link?

Great point! Thank you! This is the kind of input I was looking for.. I've been so stressed with work I miss the basics!

I'll be back!

 

[raysupra]

check fuses.. how do your grounds look? have you tried adding a ground or two to the engine/chassis..
You you believe the IG signal is bad.. put a wire in the female and run it in your car and get under your collum and start probing for continuity theirs two IG's on the start switch so you should have continuity at one.. have you even glanced at the Electrical schematics?

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=CH&P=2

electrical charging schematics..
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=D&P=3
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=D&P=6

 

[ifyouaint1sturlast]

check fuses.. how do your grounds look? have you tried adding a ground or two to the engine/chassis..
You you believe the IG signal is bad.. put a wire in the female and run it in your car and get under your collum and start probing for continuity.. have you even glanced at the Electrical schematics?

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=CH&P=2

Ray, I appreciate your help but this is a more advanced problem than basic grounds or "follow the book" methods. Before I went out (in the rain) and tested the IG signal I was getting feedback from people if that could be the problem or not, I'm not incapable. I assure you I'm more electrically inclined than you're giving me credit for, I've just been looking over something which is why I am reaching out to the community for help. I wired this 2JZ into my Supra by myself, I've glanced at the schematics.

Thanks for your help and input though. All is appreciated!

 

[raysupra]

autozone and or parts stores also sell crappy alternators and starters.. lots of people have starter solenoid and starting problems due to crappy refurbished starters..
It Could have passed their test, I dont know how they test them.. but still not be Charging.. just throwing ideas. out their...

 

[ifyouaint1sturlast]

autozone and or parts stores also sell crappy alternators and starters.. lots of people have starter solenoid and starting problems due to crappy refurbished starters..
It Could have passed their test, I dont know how they test them.. but still not be Charging.. just throwing ideas. out their...

It's the stock Denso alternator

 

[raysupra]

how much did you drive the car after the swap was complete? alt definitley could be bad.. I just replaced three on my friends 2jzge 90... lol kept spitting out bad alternators.. soo.. If you drove your car around before for a week or two and everything was fine... your battery could have gone bad because your alt was going out.. thus using more battery power than it should have and killing your battery.. and will only kill another battery.

you running the a340e? Jw

If your positive its the wiring.. then just test it thats why I gave you the schematics since you said " I'm Positive Its the Wiring".. start testing continuity on your IG wire if you think its that.. just process of elimination..I'm just trying to help I could just watch..